Refrigerated fraction collector apparatus



March 7, 1937 N. ANDROS REFRIGERATED FRACTION COLLECTOR APPARATUS 2 Sheets-Sheet 1 Filed Feb. 2, 1966 INVENTOR NICHOLAS ANDROS 50 M {CW ATTYS.

N. ANDROS March 7, 1967 I I REFRIGERATED FRACTION COLLECTOR APPARATUS F'iled Feb. 2, 1966 2 Sheets-Sheet 2 FIG; 94\Ir IINVENTOR NICHOLAS ANDROS BY wmf United States Patent 3,307,371 REFRIGERATED FRACTION CGLLECTOR APPARATUS Nicholas Andros, 7736 W. Lake St., Morton Grove, Ill. 60053 Filed Feb. 2, 1966, Ser. No. 524,542 Claims. (Cl. 62234) This invention relates generally to fraction collectors and more particularly to the provision of 'a novel refrigerated fraction collector apparatus operated by the forced circulation of cooled dehumidified air through the fraction collector chamber.

Fraction'collectors are devices commonly used to collect successively dispensed fluid samples subsequent to their undergoing separation and/or analysis by means of distillation or passage through a chromatographic column. The fraction collector generally comprises a turntable mounted for rotation with a metal housing, said turntable having concentric rows of small openings arranged inwardly of the periphery of the turntable. Suitable drive means, timing means, cam means and gear means are provided to rotate the turntable in predetermined increments of movement coordinated with the dispensation of the fluid samples. In most instances, the turntable is formed of several discs mounted on a hub spaced one from the other coaxially along the hub. The bottom disc is preferably imperforate while the concentrically arranged openings are provided in the other discs. The discs 'are mounted on the hub so that the openings are aligned so as to receive containers, such as test tubes therein. Thus the metal surface area interior of the fraction collector chamber is of a substantial amount. Means such 'as drop counters, timers and similar apparatus are provided to be positioned successively over the containers as the turntable rotates. Likewise means are provided to move the dropping means or spout from row to row radially inward along the turntable so that when one revolution of the turntable is completed, the spout is positioned to dispense samples into containers arranged in the second or other rows. The discs are arranged to permit circulation of air through the turntable apparatus.

Often it is necessary to use procedures involving temperature unstable ingredients, the characteristics thereof being adversely affected by room temperature. Under such conditions, it is desirable to provide refrigeration to lower the ambient collecting temperature so as to preserve the character of the samples as they are taken off. When such ingredients are used, the receiving containers must be provided with cooling means so as to maintain cool ambient temperatures surrounding the samples as they are taken off. Moreover, under such circumstances, it is often necessary to cool the column or separation means so that the material being analyzed does not change in composition characteristics due to ambient temperature. Fraction collectors heretofore provided were not adapted for refrigeration. One disadvantage was that the available area within which to place cooling coils was extremely limited. Secondly, the problem of frost or drippage within the fraction collector housing was a substantial one and ordinary means of refrigeration could not be applied principally because of the considerable metal surface area disposed within the housing. The simple expedient of passing cool air into the housing area was not ordinarily deemed feasible. Moreover the chances of achieving a temperature balance within the housing were thought extremely small.

Another substantial disadvantage encountered in adapting the known fraction collector to refrigeration would be the expected necessity for providing jacketing around the collector housing to enable circulation of cooling medium to cool the interior of the housing. Therefore it was believed hardly possible to 'adapt the ordinary fraction collector to use for procedures requiring refrigeration. Such procedures were carried out normally by providing individual cooled receiving containers for the samples and manipulating said containers manually or operating the entire experiment in the confines of a cold room. The large number of containers required for the first mentioned procedure and the resultant difficulty in achieving the successful manipulation of said individual containers was an obstacle thought not surmountable. The ordinary fraction collector had permitted taking off of any dozens of samples continuously and automatically. While it was desirable to extend the benefits of automatic turntable operation to procedures requiring refrigeration of the receiving containers, no means had occurred heretofore to provide a reasonably practical solution.

Accordingly, it is the object of this invention to provide a refrigerated fraction collector which comprises a successful adaptation of the ordinary fraction collector to refrigerated use and eliminates the problems enumerated above and thought to be insurmountable.

Another object of this invention is to provide a refrigerated fraction collector operated by means of the continuous circulation of chilled air through the chamber housing, and means 'are provided to dehumidify the air passed through the housing so that frost will not accumulate within the fraction collector housing.

Another object of the invention is to provide a refrigerated fraction collector characterized by a housing, the interior of which is lined with thermal insulation material.

Another object of the invention is to provide a refrigerated fraction collector apparatus which includes a turntable arranged mounted for rotation within a housing so as to occupy substantially the full area therewithin, inlet and outlet ports provided in the housing and communicatively arranged respectively to introduce and withdraw air to and from the housing, heat exchanger means arranged exterior of the fraction collector housing and adapted to receive the warm air from the interior of the said housing and to introduce cool air into the interior of said housing, said heat exchanger means comprising a first and second heat exchanger each having a primary coil through which refrigerant is pumped and said second heat exchanger means having a secondary coil through which antifreeze fluid or similar coolant is circulated and means are provided for directing the warm air from the interior of the fraction collector housing successively through said first and second heat exchangers and returning the air chilled and dehumidified, back into the fraction collector housing.

A further object of the invention is to provide means for circulating a coolant through the secondary heat exchanger and a cooling jacket being provided surrounding a chromatographic column for cooling same.

A yet further object of the invention is to provide the heat exchanger means as described above encased in a cast polyurethane block entirely surrounding both heat exchangers and air circulating means, namely a blower fan.

Another object of the invention is to provide an automatic defrost mechanism for the refrigerated fraction collector as above described.

Still other objects and advantages of the invention will become evident to the skilled artisan as a description of the preferred embodiment of the invention is set forth hereinafter with reference to the accompanying drawings. It is understood that many variations in relative size and other dimensions may occur Without departing from the concept and scope of the invention as defined in the claims.

In the drawings:

FIG. 1 is a diagrammatic perspective view of the refrigerated fraction collector constructed in accordance with the invention.

FIG. 2 is a diagrammatic plan view of the interior floor of the housing or cabinet containing the fraction collector turntable, same graphically showing the optimum location of the air inlet and outlet in accordance with the inventron.

FIG. 3 is a schematic representation of the heat exchanger means, and the refrigerant and coolant circulation means in accordance with the invention.

FIG. 4 is a perspective view of the heat exchanger means in accordance with the invention.

The refrigerated fraction collector in accordance with the invention has means provided to forcibly circulate chilled, dehumidified air through a plastic foam insulated inner chamber housing the turntable of the fraction collector.

Refrigeration is accomplished by exhausting the warm air in the fraction collector inner chamber. The thus exhausted air then is directed successively across a pair of heat exchangers, the first of which has one set of coils through which refrigerant, such as Freon, is circulated and the second has a pair of coils, one of which carries an antifreeze type solution circulated therethrough, and the other carries the refrigerant. The refrigerant carrying coils of the first and second heat exchanger are connected in parallel to the delivery and return lines of a compressor apparatus. Warm air passes across the coils of the first heat exchanger and is cooled. The thus cooled air then is passed over the second pair of coils. The antifreeze carried in the second heat exchanger is cooled both by the refrigerant passing through the second heat exchanger and by the chilled air passed thereover from the first heat exchanger. A sharp temperature drop is experienced by the air passing over the second heat exchanger to cause any moisture present in said chilled air immediately to condense on the second heat exchanger coils to dehumidify the air. Once past the second heat exchanger, the thus chilled, dehumidified air is directed by a blower into the inner chamber of the fraction collector. The circulation of the chilled, dehumidified air drops the interior temperature of the chamber to a desired point, which of course may be controlled as desired by a thermoregulator of known construction. The sharp freeze undergone by the air upon contact with the coils of the second heat exchanger is sufficient to prevent the chilled air introduced into the collector chamber from carrying moisture into the inner chamber sufficient to condense upon the interior surfaces either of the chamber or the metal surfaces of the fraction collector turntable. Thus frost and commonly expected drippage is avoided.

The entire inner surface of the fraction collector chamher is lined with foam type plastic thermal insulation and may further be lined with a secondary surrounding jacket of thermal insulation. The optimum location of the inlet and outlet ports in the floor of the fraction collector housing is very important to achieve proper uniform circulation of cool air throughout the interior of said chamber. Likewise it has been found that an optimum dimensional relationship exists between the relative diameters of the inlet and outlet ports. Means also are incorporated in the system automatically to defrost the coils of the secondary heat exchanger at predetermined time intervals. The automatic defrosting means comprises a timer operative upon a solenoid operated valve, and upon the compressor, to feed the hot gas from the return line of the compressor to the refrigerant carrying coils of the first and second heat exchanger at suitable intervals bypassing the evaporator of the compressor.

Conduit means are provided as well as suitable pump means to direct the antifreeze of the secondary heat exchanger through a jacket surrounding a chromatographic column so that the cooled antifreeze solution is circulated to cool the column as desired. Valve means controlling the amount of refrigerant permitted to pass through the refrigerant carrying coils of the second heat exchanger is provided so that the column temperature may be maintained at a desired temperature level.

Referring now to the drawing, the refrigerated fraction collector in accordance with the invention is designated generally by reference character 10 and comprises a fraction collector housing 12 mounted on a framework 14. Interior of the framework 14, a bottom shelf 16 is provided suitably braced for accommodating a refrigerant compressor apparatus 18. The heat exchanger means 20 according to the invention is mounted to the framework at the upper portion 15 thereof by means of brackets 22 and 24.

A turntable 26 is mounted for rotation within the inner chamber 28 of housing 12. The turntable 26 preferably consists of a plurality of discs 30 mounted in coaxial spaced relationship on a hub 32 for rotation within the housing 12, and occupies a substantial area interior of the housing. Suitable drive means, timing means, cam means and gear means (not shown) are provided within the hub 32 so as to rotate the turntable in successive increments of movement, generally according to apredetermined program. The housing 12 has a floor 34 and a top wall 36, opposite side walls 38 and 40 as well as front and rear walls 39 and 41. The top wall 36 is provided with an opening 42 coaxial with the turntable 26 so that said turntable 26 may be seated therethrough onto the hub 32. Suitable handles 44 may be provided on the uppermost disc of the turntable 26 to facilitate removal of the turntable from the housing 12. A suitable hinged cover 46 also may be provided to seal the opening 42 during the operation of the collector 10. The cover 46 is provided with suitable port means 48 so that samples may be dispensed into containers 50 seated in the turntable and aligned with said port means 48.

The turntable 26 is provided with concentric rows 52 of small circular openings 54 adapted to receive containers 50 such as test tubes. A suitable vertical post 56 may be provided secured either to the housing 12 or through the housing for securement on framework 14 to permit mounting of analytical apparatus (not shown) or the jacketed chromatographic column 58 thereon. Suitable measuring mechanisms such as drop counters and the like (not shown) may be provided for metering the fractions to be deposited in each of the test tubes as they are arranged in the rows 52 of the turntable 26. Control and positioning means also may be operatively incorporated in the apparatus so as to coordinate the rotation of the turntable 26 with the delivery of the discrete fractions from the column 58. Because such control means do not form any part of the invention, they are not illustrated or further described herein. They are conventional and readily available.

The floor 34 of the fraction collector housing 12 is provided with a pair of ports 60 and 62 comprising the air inlet and the air outlet ports respectively of the housing. The air outlet port 62 is located closely adjacent the hub 32 at a location equidistant from the side walls 38, 40 of the cabinet and closer to the axial center of the hub than to the rear wall 41 of the cabinet.

Directing attention to FIG. 2, the optimum relative location of ports 60 and 62 may be plotted with respect to the turntable circumference. The center of port 60 is located on a line tangent to the circumference of the turntable whose distance from the center of the turntable is r, where r is defined as the radius of the turntable. Port 62 is located so that its center is placed from the center of port 60 on the circumference of turntable 26, and a distance equal to /2 r, one-half the radius of the turntable taken from the center of said turntable. Exhaust 62 is chosen of a diameter twice that of inlet port 60. The combination of most optimum location and relative size has been empirically found to be very important in achieving uniform circulation of the chilled air through the inner chamber 28 of housing 12. The turntable acts to deflect and guide the air evenly throughout the housing interior because the inlet is located at the circumferential edge of the turntable. About half the intake is guided through the turntable to the outlet port while the remainder is deflected along the walls of the housing to said outlet port.

Directing attention now to FIG. 4, wherein the heat exchanger means according to the invention is illustrated in detail, the heat exchanger means being generally designated by reference character 20 and comprises a pair of heat exchangers 64, and 68, a centrifugal blower 70 and necessary conduit connections being entirely encapsulated, except for protruding conduit connections, within a solid block 72 of polyurethane foam type plastic material. Inlet and outlet ports 74 and 76 respectively are provided with the ends thereof projecting through suitable rubber gaskets 78, 80 from the polyurethane block 72. Suitable mounting means are provided, namely brackets 22 and 24, by embedding a length of framing member 86 within the polyurethane block 72. The pair of brackets 22, 24 extend from the block and can be secured by bolt means or the like onto the upper cross member of the frame work 14 so that the block 72 is mounted flush with the upper plane of the framework 14 and the inlet and outlet and gaskets 78, 80 extend through the ports 60 and 62 respectively and open flush with the floor 34 of the housing 12.

In order to manufacture the heat exchanger means according to the invention, the components thereof, including the blower 70 (except for the motor thereof) are placed in a mold at their proper, predetermined, relative positions with all components which are to be embedded included in the mold encased in a metal housing 73 with the conduit means extending outward thereof. A selected foaming type polyurethane plastic material then is introduced into the mold with the proper catalyst and expanded so as to result in a full encapsulation of the housing. The motor housing 71 of the blower 70 also is arranged to extend outwardly from the block 72 with the fan portion 73 thereof within housing 73.

The heat exchanger means 20 comprises a first heat exchanger 64 and a second heat exchanger 66. The first heat exchanger 64 has an elongate, continuous coil 88 formed of hollow tubing and arranged within a frame 90 to permit the passage of air therepast. Conduits 92 and 94 function as entry and exit means for the refrigerant and extend from the frame 90 to the exterior of block 72, said conduits being linked by T-connections 91 and 93 to the delivery and return lines 96 and 98 respectively of the compressor apparatus 18. The second heat exchanger 66 is formed of a network comprising a pair of coils 100 and 102 also formed using continuous tubing. The pair of coils are arranged side by side in an open framework 104 in a warp configuration woven across the framework 104. Each parallel segment of the tube pairs is spaced from the adjacent segment so as to permit passage of air therebetween. The first coil 100 has ends 106 and 108 extending from the framework 104 and of length sufficient to extend outward from the block 72. Likewise, the second coil 102 has ends 110 and 112 also of suflicient length to extend from the framework 104 through the block 72 to project therefrom.

The first coil 100 is linked by exterior conduits 114 and 116 to the jacket 118 of chromatographic column 58 through a suitable circulating pump 120 mounted on the plate or shelf 16 of the framework 14. An antifreeze type coolant, such as ethylene glycol, is circulated through the system comprising coil 100, conduits 114 and 116, jacket 118 and pump 120.

The second coil 102 of heat exchanger 66 has line 110 and 112 which extend outward of the framework 104 and through the block 72 to terminate exterior of said block 72. Lines 110 and 112 are linked by T-connectors 91 and 93 respectively to the delivery and return lines 96 and 98 respectively of the compressor apparatus 18. A control valve 128 may be interposed in either lines or 112 to control the quantity of refrigerant permitted to pass through coil 102.

The temperature of antifreeze solution circulated through coil 100 is controlled by controlling the quantity of refrigerant passing through coil 102. While a certain amount of cooling of said coolant in coil 100 is caused by the passage of the cool air from the first heat exchanger 64, the principal cooling is effected due to the refrigerant passing through the coil 102. Hence, control of the flow of refrigerant in coil 102 will control the temperature of the coolant fed to the column jacket 118.

The first heat exchanger is fed along line 96 from the compression chamber 130 of the compressor apparatus 18 and across a suitable moisture trap 132, past the window 134 of a suitable moisture detector 136 to a terminal expansion valve 138 disposed closely adjacent the polyurethane block 72 thence via line 96 to T-connector 91 and through respective conduits 92 and 1 10 into heat exchangers 64 and 66 respectively. When the compressed refrigerant, say Freon, in the liquid state, is passed through the terminal expansion valve 138 it changes from the liquid state to a gaseous state and hence withdraws heat from the surrounding environment. As the refrigerant leaves the first and second heat exchangers via conduits 94 and 112 respectively via the T-connector 93 to the return line 98, it is in a heated, gaseous state and is delivered directly to the pump 140 of the compressor apparatus 18. There the hot gas is pumped across an evaporator 142 along conduit 144 and thereafter, by way of conduit 146 to the compressor chamber 130 and then pumped from the compression chamber 130 to the heat exchangers 64 and 66 via the moisture removing means 132, the moisture detector 136, the terminal expansion valve 138, etc.

A conduit 148 is provided linking the inlet 150 of the evaporator 142 through a solenoid operated control valve 152 to the delivery line 96 on the heat exchanger means side of terminal expansion valve 138 so as to effectively by-pass the evaporator 142 and compression chamber 130. Conventional timing control means, such as timer 154 and terminal board 156, including switch 158, in the power supply line to the compressor bar 160, are provided. The control valve 152 is normally closed. At suitable time intervals, the timer 154 operates to shut off the fan and open valve 152.

As long as the timer 154 has not activated the solenoid valve 152 to open same, all the gas pumped from the circulating pump 140 to the evaporator 142 is pumped to the compressor chamber 130 and thereafter to the heat exchangers 64 and 66. When the timer 154 operates, the hot gas is fed-not into the evaporator,but into the delivery line 96 to the first and second heat exchangers 64 and 66.

The available surface area of the second heat exchanger which is exposed to the air from the first heat exchanger is substantially greater than the exposed surface area of the first heat exchanger due ot the pair of coils L100, 102.

The air passing across the heat exchanger means 20, particularly across the second heat exchanger 66, will cause a formation of a substantial quantity of ice on the coils and defrosting of the coils is necessary at suitable time intervals. For this purpose the timer 154 operates to open the solenoid operated valve 152. In this manner the ice on the coils of the heat exchangers is melted by the hot gas fed through coils 88 and 102, and suitable means are provided to tap off the resulting water from the housing 3. During this time period, the blower 70 and pump 120 is shut off. Defrosting takes a very short period of time and then timer 154 operates to close the valve 152 and activate the blower 70, fan 160 and the pump 120. At the defrost stage, when blower means 70 is shut off, with concurrent shut off of circulating pump 120, flow of air to the housing and of coolant to the column is stopped and both the column and the housing interior are maintained at a desired cool temperature not withstanding the defrosting taking place on the heat exchanger coi'ls.

The first and second heat exchangers 64 and 66 are disposed in the housing 73 within block 72 so that air exhausted from the fraction collector chamber is passed first through the first heat exchanger and then passes directly across the second heat exchanger to the blower 70.

One will note that the ordinary fraction collector apparatus has been converted by means of the invention to a refrigerant apparatus. The relative simplicity of the component parts, most of which are standard components and readily available, is a characteristic advantage of the invention. The framework 14 may be substantially enclosed by :panels with control means, etc., mounted to such panels. Many variations in size, arrangement, modifications, etc. of the component elements of the invention may occur to the skilled artisan without departing from the concept and scope of the invention as defined in the accompanying claims:

I claim:

1. A refrigerated fraction collect-or apparatus comprising an enclosed, thermally insulated hollow housing, a turntable mounted within the said housing and adapted for step-wise rotation within said housing, said turntable having openings arranged therein for receiving sample collecting containers, removable cover means for said housing adapted sealingly to cover said housing and having a port therein for introduction of samples successively to the sample collecting containers as the turntable rotates, a support framework for said housing, a refrigerant compressor apparatus mounted on the framework, heat exchanger means mounted on said framework closely adjacent said housing, said housing including a floor portion having an air inlet port and an air outlet port formed therein, said heat exchanger means communicating to said respective ports, blower means to circulate air between the interior of the housing and through said heat exchanger means, conduit means communicating between the refrigerant compressor and the heat exchanger means, enclosure means for accommodating said heat exchanger means and said blower means and said enclosure means being encapsulated in a block of expanded foam type plastic insulating material, and said heat exchanger means comprising first and second heat exchangers arranged in said enclosure means with the blower means adjacent said second heat exchanger to permit the circulation of air along a path defined by the interior of the housing through the outlet port in the floor of the housing, across the first and second heat exchangers, to the blower means and through the inlet port of the housing to the interior of the housing, said first and second heat exchangers each havingprimary coils for the passage of refrigerant therethrough and tube link means connecting said respective primary coils with the conduit means, one of the heat exchangers having a secondary coil arranged therein in heat exchange relation to the primary coil thereof, a fluid circulating system communicating with said secondary coil for directing antifreeze type coolant therethrough, whereby moisture carried by the cooled air is condensed on the coils of the heat exchanger means so that chilled, dehumidified air is delivered by the blower means to the inlet port in the floor of the housing and into the interior of the housing.

2. The apparatus as claimed in claim 1 in which said primary coils are connected in parallel with said conduit means.

3. The apparatus as claimed in claim 1 in which the secondary coil is located in the heat exchanger which is closest to the blower.

4. The apparatus as claimed in claim 1 in which said fluid circulating system includes a jacketed chromatographic column arranged exterior of the apparatus whereby the antifreeze type toolant is circulated through the jacket to cool the column.

5. The apparatus as claimed in claim 1 in which the outlet port of the housing is of a diameter substantially twice the diameter of the inlet port of said housing.

6. The apparatus as claimed in claim 1 in which bypass means is arranged between the compressor and the heat exchanger means for directing hot refrigerant gas prior to compression to the primary coils of the heat exchangers to defrost the heat exchangers, said bypass means including valve means and timer means to effect the bypass at selected time intervals.

7. The apparatus as claimed in claim 4 in which valve means are provided to vary the refrigerant directed through the primary coil of the second heat exchanger to control the temperature of the coolant passed through the said jacket.

8. The apparatus as claimed in claim 3 in which the outlet port is located offset from the axial center of the turntable.

9. The apparatus as claimed in claim 1 in which the center of the inlet port is located on a line tangent to the circumference of the turntable whose distance from the center of the turntable is defined as the radius of the turntable, and the center of the outlet port is located from the center of the inlet port and a distance equal to one-half the radius of the turntable taken from the center of the turntable.

10. The apparatus as claimed in claim 9 in which the diameter of the inlet port is one-half of the diameter of the outlet port.

References Cited by the Examiner UNITED STATES PATENTS 6/1959 Jacobs 62--234 X 5/1961 Happer 62381 X 

1. A REFRIGERATED FRACTION COLLECTOR APPARATUS COMPRISING AN ENCLOSED, THERMALLY INSULATED HOLLOW HOUSING, A TURNTABLE MOUNTED WITHIN THE SAID HOUSING AND ADAPTED FOR STEP-WISE ROTATION WITHIN SAID HOUSING, SAID TURNTABLE HAVING OPENINGS ARRANGED THEREIN FOR RECEIVING SAMPLE COLLECTING CONTAINERS, REMOVABLE COVER MEANS FOR SAID HOUSING ADAPTED SEALINGLY TO COVER SAID HOUSING AND HAVING A PORT THEREIN FOR INTRODUCTION OF SAMPLES SUCCESSIVELY TO THE SAMPLE COLLECTING CONTAINERS AS THE TURNTABLE ROTATES, A SUPPORT FRAMEWORK FOR SAID HOUSING, A REFRIGERANT COMPRESSOR APPARATUS MOUNTED ON THE FRAMEWORK, HEAT EXCHANGER MEANS MOUNTED ON SAID FRAMEWORK CLOSELY ADJACENT SAID HOUSING, SAID HOUSING INCLUDING A FLOOR PORTION HAVING AN AIR INLET PORT AND AN AIR OUTLET PORT FORMED THEREIN, SAID HEAT EXCHANGER MEANS COMMUNICATING TO SAID RESPECTIVE PORTS, BLOWER MEANS TO CIRCULATE AIR BETWEEN THE INTERIOR OF THE HOUSING AND THROUGH SAID HEAT EXCHANGER MEANS, CONDUIT MEANS COMMUNICATING BETWEEN THE REFRIGERANT COMPRESSOR AND THE HEAT EXCHANGER MEANS, ENCLOSURE MEANS FOR ACCOMMODATING SAID HEAT EXCHANGER MEANS AND SAID BLOWER MEANS AND SAID ENCLOSURE MEANS BEING ENCAPSULATED IN A BLOCK OF EXPANDED FOAM TYPE PLASTIC INSULATING MATERIAL, AND SAID HEAT EXCHANGER MEANS COMPRISING FIRST AND SECOND HEAT EXCHANGERS ARRANGED IN SAID ENCLOSURE MEANS WITH BLOWER MEANS ADJACENT SAID SECOND HEAT EXCHANGER TO PERMIT THE CIRCULATION OF AIR ALONG A PATH DEFINED BY THE INTERIOR OF THE HOUSING THROUGH THE OUTLET PORT IN THE FLOOR OF THE HOUSING, ACROSS THE FIRST AND SECOND HEAT EXCHANGERS, TO THE BLOWER MEANS AND THROUGH THE INLET PORT OF THE HOUSING TO THE INTERIOR OF THE HOUSING, SAID FIRST AND SECOND HEAT EXCHANGERS EACH HAVING PRIMARY COILS FOR THE PASSAGE OF REFRIGERANT THERETHROUGH AND TUBE LINK MEANS CONNECTING SAID RESPECTIVE PRIMARY COILS WITH THE CONDUIT MEANS, ONE OF THE HEAT EXCHANGERS HAVING A SECONDARY COIL ARRANGED THEREIN IN HEAT EXCHANGE RELATION TO THE PRIMARY COIL THEREOF, A FLUID CIRCULATING SYSTEM COMMUNICATING WITH SAID SECONDARY COIL FOR DIRECTING ANTIFREEZE TYPE COOLANT THERETHROUGH, WHEREBY MOISTURE CARRIED BY THE COOLED AIR IS CONDENSED ON THE COILS OF THE HEAT EXCHANGER MEANS SO THAT CHILLED, DEHUMIDIFIED AIR IS DELIVERED BY THE BLOWER MEANS TO THE INLET PORT IN THE FLOOR OF THE HOUSING AND INTO THE INTERIOR OF THE HOUSING. 